/*
 * Copyright (c) 2006-2011 Christian Plattner. All rights reserved.
 * Please refer to the LICENSE.txt for licensing details.
 */
package ch.ethz.ssh2.sftp;

/**
 * SFTP Open Flags.
 * <p/>
 * The following table is provided to assist in mapping POSIX semantics
 * to equivalent SFTP file open parameters:
 * <p/>
 * <ul>
 * <li>O_RDONLY
 * <ul><li>desired-access = READ_DATA | READ_ATTRIBUTES</li></ul>
 * </li>
 * </ul>
 * <ul>
 * <li>O_WRONLY
 * <ul><li>desired-access = WRITE_DATA | WRITE_ATTRIBUTES</li></ul>
 * </li>
 * </ul>
 * <ul>
 * <li>O_RDWR
 * <ul><li>desired-access = READ_DATA | READ_ATTRIBUTES | WRITE_DATA | WRITE_ATTRIBUTES</li></ul>
 * </li>
 * </ul>
 * <ul>
 * <li>O_APPEND
 * <ul>
 * <li>desired-access = WRITE_DATA | WRITE_ATTRIBUTES | APPEND_DATA</li>
 * <li>flags = SSH_FXF_ACCESS_APPEND_DATA and or SSH_FXF_ACCESS_APPEND_DATA_ATOMIC</li>
 * </ul>
 * </li>
 * </ul>
 * <ul>
 * <li>O_CREAT
 * <ul>
 * <li>flags = SSH_FXF_OPEN_OR_CREATE</li>
 * </ul>
 * </li>
 * </ul>
 * <ul>
 * <li>O_TRUNC
 * <ul>
 * <li>flags = SSH_FXF_TRUNCATE_EXISTING</li>
 * </ul>
 * </li>
 * </ul>
 * <ul>
 * <li>O_TRUNC|O_CREATE
 * <ul>
 * <li>flags = SSH_FXF_CREATE_TRUNCATE</li>
 * </ul>
 * </li>
 * </ul>
 *
 * @author Christian Plattner
 * @version 2.50, 03/15/10
 */
public final class OpenFlags {
    private OpenFlags() {
    }

    /**
     * Disposition is a 3 bit field that controls how the file is opened.
     * The server MUST support these bits (possible enumaration values:
     * SSH_FXF_CREATE_NEW, SSH_FXF_CREATE_TRUNCATE, SSH_FXF_OPEN_EXISTING,
     * SSH_FXF_OPEN_OR_CREATE or SSH_FXF_TRUNCATE_EXISTING).
     */
    public static final int SSH_FXF_ACCESS_DISPOSITION = 0x00000007;

    /**
     * A new file is created; if the file already exists, the server
     * MUST return status SSH_FX_FILE_ALREADY_EXISTS.
     */
    public static final int SSH_FXF_CREATE_NEW = 0x00000000;

    /**
     * A new file is created; if the file already exists, it is opened
     * and truncated.
     */
    public static final int SSH_FXF_CREATE_TRUNCATE = 0x00000001;

    /**
     * An existing file is opened.  If the file does not exist, the
     * server MUST return SSH_FX_NO_SUCH_FILE. If a directory in the
     * path does not exist, the server SHOULD return
     * SSH_FX_NO_SUCH_PATH. It is also acceptable if the server
     * returns SSH_FX_NO_SUCH_FILE in this case.
     */
    public static final int SSH_FXF_OPEN_EXISTING = 0x00000002;

    /**
     * If the file exists, it is opened. If the file does not exist,
     * it is created.
     */
    public static final int SSH_FXF_OPEN_OR_CREATE = 0x00000003;

    /**
     * An existing file is opened and truncated. If the file does not
     * exist, the server MUST return the same error codes as defined
     * for SSH_FXF_OPEN_EXISTING.
     */
    public static final int SSH_FXF_TRUNCATE_EXISTING = 0x00000004;

    /**
     * Data is always written at the end of the file. The offset field
     * of the SSH_FXP_WRITE requests are ignored.
     * <p/>
     * Data is not required to be appended atomically. This means that
     * if multiple writers attempt to append data simultaneously, data
     * from the first may be lost. However, data MAY be appended
     * atomically.
     */
    public static final int SSH_FXF_ACCESS_APPEND_DATA = 0x00000008;

    /**
     * Data is always written at the end of the file. The offset field
     * of the SSH_FXP_WRITE requests are ignored.
     * <p/>
     * Data MUST be written atomically so that there is no chance that
     * multiple appenders can collide and result in data being lost.
     * <p/>
     * If both append flags are specified, the server SHOULD use atomic
     * append if it is available, but SHOULD use non-atomic appends
     * otherwise. The server SHOULD NOT fail the request in this case.
     */
    public static final int SSH_FXF_ACCESS_APPEND_DATA_ATOMIC = 0x00000010;

    /**
     * Indicates that the server should treat the file as text and
     * convert it to the canonical newline convention in use.
     * (See Determining Server Newline Convention in section 5.3 in the
     * SFTP standard draft).
     * <p/>
     * When a file is opened with this flag, the offset field in the read
     * and write functions is ignored.
     * <p/>
     * Servers MUST process multiple, parallel reads and writes correctly
     * in this mode.  Naturally, it is permissible for them to do this by
     * serializing the requests.
     * <p/>
     * Clients SHOULD use the SSH_FXF_ACCESS_APPEND_DATA flag to append
     * data to a text file rather then using write with a calculated offset.
     */
    public static final int SSH_FXF_ACCESS_TEXT_MODE = 0x00000020;

    /**
     * The server MUST guarantee that no other handle has been opened
     * with ACE4_READ_DATA access, and that no other handle will be
     * opened with ACE4_READ_DATA access until the client closes the
     * handle. (This MUST apply both to other clients and to other
     * processes on the server.)
     * <p/>
     * If there is a conflicting lock the server MUST return
     * SSH_FX_LOCK_CONFLICT.  If the server cannot make the locking
     * guarantee, it MUST return SSH_FX_OP_UNSUPPORTED.
     * <p/>
     * Other handles MAY be opened for ACE4_WRITE_DATA or any other
     * combination of accesses, as long as ACE4_READ_DATA is not included
     * in the mask.
     */
    public static final int SSH_FXF_ACCESS_BLOCK_READ = 0x00000040;

    /**
     * The server MUST guarantee that no other handle has been opened
     * with ACE4_WRITE_DATA or ACE4_APPEND_DATA access, and that no other
     * handle will be opened with ACE4_WRITE_DATA or ACE4_APPEND_DATA
     * access until the client closes the handle. (This MUST apply both
     * to other clients and to other processes on the server.)
     * <p/>
     * If there is a conflicting lock the server MUST return
     * SSH_FX_LOCK_CONFLICT. If the server cannot make the locking
     * guarantee, it MUST return SSH_FX_OP_UNSUPPORTED.
     * <p/>
     * Other handles MAY be opened for ACE4_READ_DATA or any other
     * combination of accesses, as long as neither ACE4_WRITE_DATA nor
     * ACE4_APPEND_DATA are included in the mask.
     */
    public static final int SSH_FXF_ACCESS_BLOCK_WRITE = 0x00000080;

    /**
     * The server MUST guarantee that no other handle has been opened
     * with ACE4_DELETE access, opened with the
     * SSH_FXF_ACCESS_DELETE_ON_CLOSE flag set, and that no other handle
     * will be opened with ACE4_DELETE access or with the
     * SSH_FXF_ACCESS_DELETE_ON_CLOSE flag set, and that the file itself
     * is not deleted in any other way until the client closes the handle.
     * <p/>
     * If there is a conflicting lock the server MUST return
     * SSH_FX_LOCK_CONFLICT.  If the server cannot make the locking
     * guarantee, it MUST return SSH_FX_OP_UNSUPPORTED.
     */
    public static final int SSH_FXF_ACCESS_BLOCK_DELETE = 0x00000100;

    /**
     * If this bit is set, the above BLOCK modes are advisory. In advisory
     * mode, only other accesses that specify a BLOCK mode need be
     * considered when determining whether the BLOCK can be granted,
     * and the server need not prevent I/O operations that violate the
     * block mode.
     * <p/>
     * The server MAY perform mandatory locking even if the BLOCK_ADVISORY
     * bit is set.
     */
    public static final int SSH_FXF_ACCESS_BLOCK_ADVISORY = 0x00000200;

    /**
     * If the final component of the path is a symlink, then the open
     * MUST fail, and the error SSH_FX_LINK_LOOP MUST be returned.
     */
    public static final int SSH_FXF_ACCESS_NOFOLLOW = 0x00000400;

    /**
     * The file should be deleted when the last handle to it is closed.
     * (The last handle may not be an sftp-handle.)  This MAY be emulated
     * by a server if the OS doesn't support it by deleting the file when
     * this handle is closed.
     * <p/>
     * It is implementation specific whether the directory entry is
     * removed immediately or when the handle is closed.
     */
    public static final int SSH_FXF_ACCESS_DELETE_ON_CLOSE = 0x00000800;
}
